One of the age old problems with firearms is the fact many of them have a strong recoil that affects the person firing the weapon. Recoil in firearms causes problems such as flinching, jerking the gun, raising the head, stopping the swing and others. In firearms such as shotguns and rifles, the rear end of the butt stock is held against the shooter's shoulder and the recoil often causes the shooter to raise the front of the firearm each time the weapon is fired.
The amount of recoil varies depending upon the amount of explosive in the shell being fired. When using smaller caliber ammunition, M16 firearms do not need a strong recoil reduction mechanism. They typically include a recoil spring that serves both as the operating spring and as a recoil buffer. However, as the caliber of ammunition used in these firearms increases, the recoil substantially increases and can result in pain and or bruising to the shoulder area of the person firing the weapon. Recoil is partially handled, in many cases, by the addition of a recoil pad, recoil reducer, barrel porting or a compression butt plate to the firearm. However, when larger caliber ammunition is used, these partial solutions become unsatisfactory.
Alternate solutions include cutting the stock into two portions, typically by removing the butt plate, and the two portions are enabled to move relative to one another to absorb the recoil. There is shown, for example, in U.S. Pat. No. 6,637,141 to Weatherby et al., a gunstock formed with a stationary portion and a rotating portion having a flexible hinge mechanism that substantially reduces both the recoil and the tendency of the gun to move upward or jerk when it is fired. A receiver extension (buffer tube) extends through both portions. The mechanism includes a sliding pin whose head is affixed in the stationary portion and whose end extends into an arcuate channel in the rotating portion.
Thus, there is a long felt need for improved recoil mitigation for firearms of the M-16 type that retains the shape and function of the firearm.
There are also known M16 firearms with collapsible stocks. These firearms were designed to be both handier and lighter in weight than the same firearm would be with a standard stock. Collapsible stocks are a feature of a gun whereby the stock can be lengthened or shortened to fit the user, or to allow the gun to be stored more easily. The stock includes a reciprocating pin that seats in one of a plurality of grooves defined in the bottom of the buffer tube so as to lock the buffer in place during firing. By retracting the pin, the buffer tube can be moved telescopingly into and out of the buffer tube holder in the stock to adjust the length of the stock. The pin then locks the buffer tube in place before the firearm is fired.